The present invention relates to method and apparatus for casting a gasket into a cast member and more particularly, to a gasket and a positioning ring upon which the gasket is force fittingly mounted and method and apparatus for casting same.
It is conventional in septic tanks, as well as other cast members, such as concrete structures, to provide openings, within the cast member to accommodate the insertion of a pipe therethrough.
Septic tanks, as well as other similar structures, are cast in a mold assembly, typically comprised of inner and outer mold members which respectively define the interior and exterior walls thereof.
In one conventional casting operation, the outer walls or jackets defining the outer periphery of the cast member are swingably mounted near their lower ends. Preparatory to casting, the pivotally mounted outer jackets are swung to an upright, vertical (i.e., xe2x80x9cclosedxe2x80x9d ) position in readiness for receiving the cast material.
Cast members, such as septic tanks are typically four-sided, rectangular-shaped members having at least one opening provided one or more of its side walls.
One technique presently being utilized to define the opening in a side wall of the cast member is to fixedly secure a metal or plastic mandrel to the inner wall of an outside jacket A one-piece pipe seal is releaseably mounted upon the mandrel, whereupon the outer jacket is swung to the upright vertical position in readiness for pouring of the cast material. The pipe seal has an outer peripheral flange, which is anchored within the cast material.
After the cast material has set, the outer jackets are opened to remove the cast member. The mandrel pulls away from the pipe seal, which is retained within the sidewall of the cast member.
The pipe seal typically has an integral central portion which seals the side wall in the event that no pipe is to be inserted through that side wall and further is provided with circular sections which may be easily torn away to form an opening for accommodating two, three or four inch pipes, for example.
A pipe of the suitable diameter is inserted into the opening of the pipe seal. The pipe seal is formed of a substantially non-resilient plastic material and, at best, forms what is referred to as a xe2x80x9cdirt sealxe2x80x9d with the pipe, enabling undesirable materials to leach into the cast member, as well as, allowing undesirable materials within the cast member to seep out.
In addition, the pipe quite frequently is utilized to support internal components, such as baffles and filter systems which, due to their significant weight, as well as the weight of the pipe itself, cause the xe2x80x9cdirt sealxe2x80x9d to further weaken and deteriorate, enabling even greater seepage of undesirable materials through the xe2x80x9cdirt sealxe2x80x9d.
The present, invention is characterized by comprising method and apparatus for providing a water-tight seal for cast members, such as septic tanks and the like, wherein the water-tight seal is obtained through the use of an inexpensive and yet rugged gasket which is highly, effective in providing an excellent water-tight seal between the opening and a pipe inserted through the gasket and which further assures highly accurate positioning of the gasket within the cast member.
The present invention comprises a resilient, compressible rubber or rubber-like gasket of annular shape having a main body portion with anchoring means extending radially outwardly therefrom and joined to the main body portion by a flexing portion which is adapted to bend upon insertion of a pipe enabling one side surface of the main body portion to make surface contact with the pipe over a significant area to provide a good water-tight seal.
In addition thereto, water-energizing pockets are provided as is described in detail in U.S. Pat. No. Re 34,787 and pending application Ser. No. 08/947,755, filed Oct. 9, 1997, now U.S. Pat. No. 5,997,006 issued Dec. 7, 1999, which patents are assigned to the assignee of the present application, the teachings thereof being incorporated herein by reference thereto. The water energizing pockets further enhance the water-tight seal, as is described in detail in the aforementioned U.S. Patent and co-pending application.
An annular-shaped plastic mandrel has a radially, inwardly directed annular flange or xe2x80x9chookxe2x80x9d portion which snaps over the gasket and locks the gasket in place on the mandrel. The plastic mandrel serves as a means for defining the opening within the cast member along the interior side of the member.
The gasket assembly which is now comprised of the interlocked gasket and plastic mandrel are placed onto the metal or plastic outer, mandrel, which is typically welded or bolted to the interior surface of the swingably mounted, outside jacket. The jacket is then moved to the upright (xe2x80x9cclosedxe2x80x9d) position preparatory to the casting operation, whereupon the cast material is poured into the mold. The side of the plastic mandrel opposite the hook portion joined to the gasket engages the interior wall of the inside jacket and thereby cooperates with the metal or plastic outer mandrel to properly position and space the gasket between the interior walls of the inner and outer mold members.
When the cast material (i.e., concrete) is cured, the outside jacket is swung away from the vertical position whereupon the outside jacket and outer mandrel are stripped away from the gasket assembly, leaving the gasket and plastic mandrel anchored within the cast member. The, plastic mandrel is provided with a left-hand portion of reduced diameter relative to the portion adjacent. thereto, forming a shoulder which locks the plastic mandrel within the cast member due to the cast material filling in the portion of reduced diameter and resting against the shoulder to prevent the plastic mandrel from being dislodged from the cast member. Although the hook portion of the plastic mandrel is maintained within one of the water energizing pockets, the water energizing pocket, which is effective upon insertion of the pipe, is on the opposite side of the plastic mandrel so that the plastic mandrel does not in any way reduce the effectiveness of active water energizing pocket.
In one preferred embodiment, the plastic mandrel may be fitted with a hollow, annular-shaped pipe stop which is snap fitted to the end of the plastic mandrel remote from the gasket. The pipe stop extends radially inward by a distance sufficient so as to be engaged by the end of a pipe inserted into the gasket causing the pipe to rest against the stop and thereby control the depth to which the pipe is inserted into the opening in the cast member. As is described in detail in the aforementioned U.S. Pat. Nos. Re 34,787 and 5,997,006, the gasket, together with its water energizing pocket provides an excellent water-tight seal.
As another preferred embodiment of the present, a cover plate may be snap-fitted over the end of the plastic mandrel opposite the hook shaped end, providing a water-tight closure for the cast member. The cover plate is formed of a suitable plastic material which may be cut away at some future time to provide for insertion of a pipe.
Although the outer jacket swings away from the cast member after it has been cured, moving along an arcuate path, the gasket is sufficiently yieldable to enable the outer jacket and outer mandrel to be readily and easily stripped from the gasket without any undesirable displacement, due to the resiliency and compressibility of the gasket. The plastic mandrel further provides the function of assuring proper placement and positioning of the gasket between,the inner and outer mold members, the need for providing a mandrel which extends all the way to and engages the inner mold member, is thus eliminated.
In still another preferred embodiment of the present invention, a reusable mandrel is secured to the swingable jacket of a mold assembly. The mandrel is comprised of a slightly tapered inside portion and a more severely tapered outside portion separated by a gap which forms a recess for receiving the gasket. A gasket of the type described hereinabove having water-energizing pockets, is stretched over the mandrel, which is preferably formed of plastic so that the pipe engaging portion of the gasket is seated in the recess. The mold assembly jacket is then swung to the closed position whereupon the cast material is poured into the mold assembly. After the cast material (preferably concrete) is cured, the jacket is then opened whereupon the mandrel is stripped out through the gasket. Due to the design of the mandrel such that the diameter of the inside portion of the mandrel adjacent the recess is smaller than the diameter of the outside portion of the mandrel adjacent brand on the opposite side of the recess, the gasket freely rolls over and away from the mandrel, enabling removal of the mandrel.
The mandrel may have a shoulder machined at its rear end to provide a pipe stop, assuring that when a pipe is inserted into the opening, the pipe stop limits the depth of insertion of the pipe into the opening in the cast member, preventing unwanted penetration into the interior of the structure.
In still another embodiment, the interior end of the mandrel may be designed to have an axial length which is less than the thickness of the cast member (typically of the order of 0.50 inches), thereby cooperating with the core and jacket members of the mold assembly to form a block-out area at each location where a gasket is placed on order to initially close the block out openings, while selectively enabling breakout of the block-but area according to the number and position of pipes to be inserted into the cast member.
A plastic cap may be snapped onto the interior end of the plastic mandrel for use as a temporary plug or block-out, as an alternative to the block-out area mentioned hereinabove.
In applications where septic tanks require baffles anchored in the wall, the mandrel can be provided with a machined area to lock a fixture onto the tank, which fixture is provided with fasteners for the baffle assembly which can be locked into the concrete when cast, enabling a baffle to be simply snapped onto the fixture at the job site.
It is therefore one object of the present invention, to provide novel method and apparatus for providing an inexpensive and yet highly effective gasket within a cast member to provide a water-tight seal not heretofore capable of being provided at such low cost.
Another object of the present invention to provide novel method and apparatus for providing an inexpensive and yet highly effective gasket within a cast member to provide a water-tight seal which is yieldable under load and yet retains the water-tight seal even upon up/down or left/right movement of the pipe.
Still another object of the present invention is to provide a novel method and apparatus for casting a gasket within a cast member wherein a plastic mandrel is utilized to accurately control the proper positioning of the gasket within the cast member, and to accurately control the inside diameter of the opening.
Still another object of the present invention is to provide, a novel gasket/mandrel assembly comprised of a gasket and mandrel which is snap-fittingly coupled to the gasket so that the gasket/mandrel assembly may be simply and readily inserted into a mold assembly as a unit for producing a cast member having a gasket embedded therein.
Still another object of the present invention is to provide a novel method and apparatus for casting a gasket within a cast member in which the gasket is provided with novel water energizing pockets, one of which is utilized to snap fittingly couple the gasket to the plastic member to make a composite, unified gasket/mandrel assembly which simplifies storage, shipping, handling and assembly into a casting mold.
Still another object of the present invention is to provide a novel gasket/plastic mandrel assembly which includes a snap-on pipe stop member for controlling the depth of insertion of a pipe into the gasket.
Still another object of the present invention is to provide a novel method and apparatus for casting gaskets into a cast member in which a plastic mandrel/gasket assembly is further provided with a cover plate to provide a water-tight seal in the cast member, which cover plate may be cut away to provide an opening for a pipe line at some future time.
Still another object of the present invention is to provide a novel method and apparatus for casting gaskets into an opening in a cast member in which a gasket is mounted upon a reusable mandrel which is removed by being drawn through the gasket when the cast member has set.
Still another object of the present invention is to provide a novel method and apparatus employing a reusable mandrel assembly adapted for providing a block-out area within a cast member.
Still another object of the present invention is to provide a novel method and apparatus for casting gaskets into a cast member employing a reusable mandrel assembly which may be fitted with a fixture embedded within the cast member for snap-fittingly mounting a baffle thereto.